A battery of coke ovens is provided along each side with a row of doors each opening into a respective end of a respective coke oven. These doors are relatively tall and massive, as they serve to hold the entire coal charge inside the respective coke oven during the distillation thereof. These doors must also form a tight seal with the respective surrounding frame aperture so that on the one hand air cannot enter the coking chambers to allow combustion of the coal, and on the other hand the leakage of dangerous gases such as carbon monoxide to the surrounding areas is prevented. At the same time the doors must be able to withstand the enormous heat generated during the coking process.
In order to push the coke charges out of the ovens after the coking process is completed, it is necessary to remove the doors from the ends of each coking oven. Even after opening the heavy latches that hold them shut, these doors normally remain tightly lodged in place as a result of accumulations that collect during the coking process. Thus, the doors must be broken free before they can be extracted from the ovens.
Generally, a door extractor engaging coacting elements of the oven doors is operated so as to lift them slightly. To this end an operator normally supervises the door extraction, ensuring that each door is raised sufficiently within its frame aperture, in which the door is received with considerable play, so as to break the door free of the frame. Then each door is withdrawn.
After this withdrawal the door is normally transported to a cleaning machine which scrapes from it and from its seal the accumulations that form during the coking process. Thereafter the door must be repositioned exactly in line with the respective frame aperture and reinserted into same. The latches are then secured and a new coking cycle may commence.
Such a procedure must be carried out with extreme care so as not to damage the seals provided on the doors and the frames. Thus it is critical that each door be lifted through a predetermined relatively short distance to break it free, since if not lifted enough the door will not be detached whereas if lifted too high it will become wedged against the upper edge of the frame. Similarly, the door must be exactly centered in front of the respective frame before it can be reinserted.